The government is planning to hand data on millions of people’s car journeys to police to use as part of their anti-terrorism work – and possibly for wider crime fighting purposes.

News of plans to transfer automatic number plate recognition (ANPR) data from cameras used to control traffic congestion and future road pricing schemes emerged in a document inadvertently leaked by the Home Office yesterday.

The leaked papers – which show disagreements between the Home Office and the Department for Transport (DfT) over the move – came as home secretary Jacqui Smith lifted Data Protection Act restrictions to allow the Metropolitan Police to use ANPR data collected through London’s congestion charging scheme in counter-terrorism work.

Police minister Tom McNulty told MPs that Smith had signed a certificate exempting Transport for London – which runs the congestion charging scheme – and the Metropolitan Police from certain provisions of the 1998 act.

This would allow bulk, real-time transfer to the police of automatic number plate recognition (ANPR) data from the cameras used to record cars entering or leaving the central London congestion charging zone.

But the Home Office has now confirmed that much more sweeping data sharing proposals are under consideration.

The experience of the last few weeks had shown that use of ANPR data from across the country was “a necessary tool to combat the threat of alleged vehicle-borne terrorism”, a home office spokesperson said.

In a reference to the disagreements within Whitehall revealed in the documents – which centre on fears that “Big Brother” style monitoring would be highly controversial and could stoke opposition to road pricing schemes – the spokesperson said: “It is right that these decisions are not taken lightly. This submission shows that the decision was subject to consideration across government.”

The move to hand swathes of ANPR data to police is the latest of a string of government data sharing proposals to emerge within the past few days.

It follows hard on the heels of prime minister Gordon Brown’s inclusion of a series of measures to increase government data sharing powers in his draft legislative programme.

The Home Office spokesperson said proposals would be developed to ensure the sharing of ANPR data with the police was “subject to a robust regulatory framework which ensures public openness”.

Using the ANPR data for wider crime-fighting is still on the agenda. The home office said no decision “had yet been made” on whether ANPR data from third parties – which could include local authorities or others involved in road pricing or congestion schemes – would be made available to the police for purposes unconnected with anti-terrorism.

“Such a decision would only be taken with wider consultation,” the Home Office spokesperson said.

A DfT spokesperson said the department “fully appreciates the importance to national security of data sharing in this case and also that any measures are sensible, proportionate and governed by appropriate protocols with clear lines of accountability”.